The term “laser” originated as an acronym for “light amplification by stimulated emission of radiation.” Today, many different types of lasers have been developed, and lasers are usefully applied in a wide variety of scientific and commercial applications. However, lasers remain an area of active scientific research and development, and new types of lasers continue to emerge, finding many new and useful applications.
One type of laser, the “optical parametric oscillators” are generally cumbersome and expensive, and too large for applications that require relatively portable sources and field usability. Another type of laser, the “Semiconductor-based quantum cascade lasers (QCLs)” have exhibited significant improvements in the last decade, but narrow linewidth tunable QCLs are based on external cavity configurations that are still relatively complicated and cumbersome, and thus relatively expensive as commercial products. Moreover, QCLs often require cooling, or only work in the pulsed mode.
Another type of laser, the “Raman fiber lasers (RFLs)” are particularly attractive sources of high intensity light at nearly arbitrary wavelengths because the gain in the fiber is achieved by stimulating coherent radiation via phonon shifts in the glasses used to make the fibers, as opposed to the fixed energy transitions in atoms or rare-earth ions used for traditional fiber amplifiers and lasers. However, work on narrow linewidth (NLW) laser sources has focused on RFLs in the near infrared (IR) regions of the spectrum, and there is no work to date on the demonstration of narrow linewidth mid-infrared RFL sources, or on the effective tuning of such RFL sources for applications such as molecular sensing or various other applications.
Improved laser technologies are desired. In particular, narrow linewidth, optionally tunable, mid-infrared Raman fiber lasers, and methods of manufacturing such lasers may prove useful for a variety of emerging laser applications.